The number of tuberculosis cases here increased slightly in 2006, and Hawai'i once again had the nation's third-highest infection rate.

The Centers for Disease Control and Prevention yesterday reported the number of Hawai'i cases per 100,000 people increased to 8.9, compared to the national average of 4.6. Only Alaska and Washington, D.C., had higher rates.

The number of Hawai'i cases totaled 115, up from 112 in 2005.

Worldwide tuberculosis is still a deadly disease with an estimated 2 billion people infected. The CDC estimates that about 9 million people become ill from TB annually. Of these, about 2 million will die.

Hawai'i traditionally has had one of the highest rates in the nation, in part because of immigration and a higher than normal incidence of cases among foreign-born citizens, including people from the Philippines, Vietnam, China and India.

The state has a broad program to thwart the spread of TB, including mandatory testing of children before they enter school and screening of restaurant workers.

That's resulted in the number of cases here falling by 37 percent during the past decade, said Dr. Jessie Wing, chief of the state Department of Health's tuberculosis control program. In 1997 the case rate for Hawai'i was 14.1.

"We remain vigilant," she said. "We're probably tracking with the U.S. in that the rates overall have gone down."

She said the state is in the process of revising administrative rules on testing to include new blood tests that are more accurate, as well as ongoing screening based on risk assessment.

The new administrative rules could include doing away with mandatory screening of school children. Wing said she hopes public hearings for the rules will be scheduled later this year.

Last year, about 50,000 people underwent skin tests, and 14.4 percent came back positive. Most of the cases were people with latent TB infections, meaning they aren't sick but have the TB bacteria in their body. People with latent infections can't spread the disease and undergo about nine months of treatment with antibiotics.

The CDC reported that TB rates among foreign-born people is 9.5 times the rate of U.S.-born people. The CDC noted TB rates declined for all ethnic minorities except Native Hawaiians, other Pacific Islanders and American Indians/Alaska Natives. Asians, blacks and Hispanics continued to have higher infection rates than whites last year, the agency said.

The state reported that 79 percent of its new cases involved foreign-born people.

Reach Greg Wiles at gwiles@honoluluadvertiser.com.